How severe is CVE-2021-33575?

CVE-2021-33575 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-33575?

CVE-2021-33575 affects the following packages: ruby-jss (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2021-33575?

Update ruby-jss to 1.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-33575 is resolved across your whole dependency graph.

How do I detect CVE-2021-33575 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ruby-jss, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-33575 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2021-33575 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-33575 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-33575?

CVE-2021-33575 has an EPSS (Exploit Prediction Scoring System) score of 2.6%, placing it in the 85th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2021-33575 published, and has it been updated?

CVE-2021-33575 was published on May 25, 2021 and was last updated on July 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎

💎 RubyGems

Not in CISA KEV

CRITICAL severity

CVE-2021-33575 — ruby-jss

CRITICAL

CVE-2021-33575 is a critical-severity (CVSS 9.8) remote code execution vulnerability in ruby-jss. A fix is available for ruby-jss — see the affected versions and patch details below.

Remote code execution in ruby-jss

Also known asGHSA-vmfh-c547-v45h

Published

May 25, 2021

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs85th percentile — riskier than 85% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-33575 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,738 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

💎ruby-jss

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

The Pixar ruby-jss gem before 1.6.0 allows remote attackers to execute arbitrary code because of the Plist gem's documented behavior of using Marshal.load during XML document processing.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`ruby-jss`	all versions	1.6.0`bundle update ruby-jss --conservative`

Affected Products

1 product · 1 configurations

Application

ruby-jsspixar

< 1.6.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ruby-jss, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ruby-jss to 1.6.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-33575 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

The Pixar ruby-jss gem before 1.6.0 allows remote attackers to execute arbitrary code because of the Plist gem's documented behavior of using Marshal.load during XML document processing.

O3 Security · Impact-Aware SCA

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